sata_svw: check DMA start bit before reset
authorDavid Milburn <dmilburn@redhat.com>
Mon, 29 Oct 2012 23:00:22 +0000 (18:00 -0500)
committerJeff Garzik <jgarzik@redhat.com>
Fri, 16 Nov 2012 04:54:41 +0000 (23:54 -0500)
commitb03e66a6be91f8389fcd902ab6c1563db1c9c06b
tree97049500a3dd0fd3c7c7801d5f6a697b006f1fb1
parentcd705d5ad49bb8894dda2726dcaef8f63ddeba43
sata_svw: check DMA start bit before reset

If kdump is triggered with pending IO, controller may not respond causing
kdump to fail.

http://marc.info/?l=linux-ide&m=133032255424658&w=2

During error recovery ata_do_dev_read_id never completes due hang
in mmio_insw.

ata_do_dev_read_id
 ata_sff_data_xfer
  ioread16_rep
   mmio_insw

if DMA start bit is cleared before reset, PIO command is successful
and kdump succeeds.

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
drivers/ata/sata_svw.c